Protein Kinases are receptor type or non-receptor type proteins, which transfer the terminal phosphate of ATP to aminoacid residues, such as tyrosine, threonine, serine residues, of proteins, thereby activating or inactivating signal transduction pathways. These proteins are known to be involved in many cellular mechanisms, which in case of disruption, lead to disorders such as abnormal cell proliferation and migration as well as inflammation.
As of today, there are over 500 known Protein kinases. Included are the well-known Ab1, Akt1, Akt2, Akt3, ALK, Alk5, A-Raf, Axl, B-Raf, Brk, Btk, Cdk2, Cdk4, CdkS, Cdk6, CHK1, c-Raf-1, Csk, EGFR, EphA1, EphA2, EphB2, EphB4, Erk2, Fak, Fes, Fer, FGFR1, FGFR2, FGFR3, FGFR4, Flt-3, Fms, Frk, Fyn, Gsk3α, Gsk β, HCK, Her2/Erbb2, Her4/Erbb4, IGF1R, IKK beta, Irak4, Itk, Jak1, Jak2, Jak3, Jnk1, Jnk2, Jnk3, KDR, Kit, Lck, Lyn, MAP2K1, MAP2K2, MAP4K4, MAPKAPK2, Met, Mer, MNK1, MLK1, mTOR, p38, PDGFRα, PDGFRβ, PDPK1, PI3Kα, PI3Kβ, PI3Kγ, PI3Kδ, Pim1, Pim2, Pim3, PKC alpha, PKC beta, PKC theta, Plk1, Pyk2, Ret, ROCK1, ROCK2, RON, Src, Stk6, Syk, TEC, Tie2, TrkA, TrkB, Tyk2, VEGFR1/Flt-1, VEGFR2/Kdr, VEGFR3/Flt-4, Yes, and Zap70.
Abnormal cellular responses triggered by protein kinase-mediated events produce a variety of diseases. These include autoimmune diseases, inflammatory diseases, neurological and neurodegenerative diseases, cancer, cardiovascular diseases, allergies and asthma, Alzheimer's disease and hormone-related diseases.
Tyrosine kinases are receptor type or non-receptor type proteins, which transfer the terminal phosphate of ATP to tyrosine residues of proteins thereby activating or inactivating signal transduction pathways. These proteins are known to be involved in many cellular mechanisms, which in case of disruption, lead to disorders such as abnormal cell proliferation and migration as well as inflammation.
As of today, there are about 58 known receptor tyrosine kinases. Included are the well-known VEGF receptors (Kim et al., Nature 362, pp. 841-844, 1993), PDGF receptors, c-kit, Flt-3 and the FLK family. These receptors can transmit signals to other tyrosine kinases including Src, Raf, Frk, Btk, Csk, Abl, Fes/Fps, Fak, Jak, Ack, etc.
Among tyrosine kinase receptors, c-kit is of special interest. Indeed, c-kit is a key receptor activating mast cells, which have proved to be directly or indirectly implicated in numerous pathologies for which the Applicant filed WO 03/004007, WO 03/004006, WO 03/003006, WO 03/003004, WO 03/002114, WO 03/002109, WO 03/002108, WO 03/002107, WO 03/002106, WO 03/002105, WO 03/039550, WO 03/035050, WO 03/035049, U.S. 60/359,652, U.S. 60/359,651 and U.S. 60/449,861, WO 04/080462, WO 05/039586, WO 06/135721, WO 07/089,069, WO 07/124,369, WO 08/137,794, WO 08/063,888, WO 08/011,080, WO 09/109,071, WO 10/096,395.
It was found that mast cells present in tissues of patients are implicated in or contribute to the genesis of diseases such as autoimmune diseases (rheumatoid arthritis, inflammatory bowel diseases (IBD)), allergic diseases, bone loss, cancers such as solid tumors, leukaemia and GIST, tumor angiogenesis, inflammatory diseases, interstitial cystitis, mastocytosis, graft-versus-host diseases, infection diseases, metabolic disorders, fibrosis, diabetes and CNS diseases. In these diseases, it has been shown that mast cells participate in the destruction of tissues by releasing a cocktail of different proteases and mediators such as histamine, neutral proteases, lipid-derived mediators (prostaglandins, thromboxanes and leukotrienes), and various cytokines (IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, TNF-α, GM-CSF, MIP-1a, MIP-1b, MIP-2 and IFN-γ).
The c-kit receptor also can be constitutively activated by mutations leading to abnormal cell proliferation and development of diseases such as mastocytosis (D816V mutation) and various cancers such as GIST (c-kitΔ27, a juxtamembrane deletion).
Sixty to 70% of patients presenting with AML have blasts which express c-kit, the receptor for stem cell factor (SCF) (Broudy, 1997). SCF promotes growth of hematopoietic progenitors, and act as a survival factor for AML blasts. In some cases (1 to 2%) of AML, a mutation in a conserved residue of the kinase domain (Kit816) resulting in constitutive activation of c-kit has been described (Beghini et al., 2000; Longley et al., 2001). This gain of function mutation (Asp to Val/Tyr substitution) has been identified in mast cell leukemic cell lines and in samples derived from patients with mastocytosis (Longley et al., 1996). Preliminary results show that this mutation is expressed in most cases of systemic mastocytosis ([˜60%], P Dubreuil, AFIRMM, study in progress on about 300 patients).